Idle Speed Control (ISC) Solenoid

An air passage by-passing the throttle valve is provided to route filtered air directly into intake manifold. ECM-energized ISC solenoid valve regulates airflow through this passage. Solenoid is located on side of throttle body.

Air is allowed to pass through ISC solenoid valve when it is energized. Solenoid is energized whenever idle speed drops to less than desired RPM due to engine load (i.e., electrical, A/C, P/S, automatic transmission in Drive, etc.). ISC solenoid valve is also energized each time engine is started and during periods of deceleration (to compensate for rich mixtures caused by a fully closed throttle). Duration of ISC solenoid valve operation is dependent on coolant temperature.